Light intensity imbalance in 2D magnetic photonic crystals with a real number in off-diagonal components of a dielectric tensor

Magneto-optical effects are caused by parameters of the off-diagonal components in the dielectric tensor of materials, which is a complex number. Because the real parts of off-diagonal components rotate the photo-induced polarization in the materials from the direction of the incident light electric field, the parts must become one of the effective parameters for light energy flow control in photonic crystals. In this study, we theoretically proposed a mechanism to realize light intensity imbalance to the left and right by inverting the sign of the real parts for 2D magnetic photonic crystals based on a finite-difference time-domain simulation and photonic band calculations. Our analyzes reveal that the maximal intensity peaks of light magnetic field distributions rotate ∼ 6 0 ∘ around the hole of the crystal at the Γ point in the Brillouin zone, and these rotations are caused by the real parts. The imbalance is caused by the deflections of light energy flow owing to the rotation, which are explained based on the following two mechanisms: the walk-off phenomenon and uneven bifurcation. Furthermore, the proposed mechanism was experimentally confirmed by observing the imbalance in the scattered light intensity from the surface of rough-cutting magnetic photonic crystals fabricated from a cerium-substituted yttrium iron garnet. The results of this study serve as a foundation for the development of light energy flow control by engineering photonic crystals using the real part of the off-diagonal components in dielectric tensors.